There is a seemingly never-ending demand in the field of data storage for optical storage media (e.g., for use as pre-recorded optical disks) having increased data storage capacity and performance. Recently, optical media, such as optical storage media, have been developed that contain semi-reflective layers that increase the storage capacity of an optical storage medium by allowing the medium to contain multiple information-bearing layers. Information can be read from a semi-reflective information-bearing layer by focusing laser light on the semi-reflective layer. Alternatively, light can be transmitted through the semi-reflective layer and focused on one or more other reflective or semi-reflective information-bearing layers. Thus, two or more information-bearing layers can be accessed independently, from one side of the medium, by using a differential laser focusing lens, and data storage capacity of the optical medium is multiplied. See, for example, U.S. Pat. No. 4,450,553 (Holster et al.), and assignee's co-pending U.S. Pat. Application, U.S. Ser. No. 08/286,289, filed Aug. 5, 1994 under the title "Dual Layer Optical Medium Having Partially Reflecting Thin Film Layer" in the name of Michael B. Hintz, and having Attorney's Docket No. 50849USA6A, each of which describe optical media containing multiple information-bearing layers.
The construction of a multi-layer optical medium, in accordance with Hintz, for example, can include a substrate, a semi-reflective layer, and a polymeric spacer layer disposed on the semi-reflective layer. Because the polymer layer contacts the semi-reflective layer, there is a need in the optical media art for a polymer layer that will adhere well to such semi-reflective layers.
Besides adhering well to a semi-reflective layer, the composition of the polymer layer will affect other aspects of the performance, stability, and ultimately the usefulness of an optical medium. For instance, a polymer layer is desirably optically clear. And, the polymer layer will typically be applied to an optical medium in the form of a liquid solution that is thereafter cured or solidified. To provide efficient processing, the uncured polymer solution should be capable of being efficiently coated onto the semi-reflective layer of an optical medium to form a smooth, uniform, coating. The polymer layer desirably cures in a relatively short period of time, and once cured, the polymer layer should exhibit good adherence to the semi-reflective layer so there will be no delamination or separation over time.